Gut decontamination or methods of poison removal in clinical toxicology

This presentation includes various methods of poison removal like emesis, gastric lavage (stomach wash), catharsis, activated charcoal, whole bowel irrigation.

1. GUT DECONTAMINATION T. SOUJANYA PHARM.D

2. CONTENT: Definition Methods of poison removal Emesis Gastric lavage (stomach wash) Catharsis Activated charcoal Whole bowel irrigation

3. DEFINITION: Gastrointestinal decontamination refers to the practice of functionally removing an ingested toxin from the gastrointestinal tract (GIT) in order to decrease its absorption. Gastric decontamination has been a cornerstone in the management of overdose for decades.

4. METHODS OF POISON REMOVAL: The various methods of poison removal from the gastrointestinal tract include: Emesis Gastric lavage (stomach wash) Catharsis Activated charcoal Whole bowel irrigation

5. 1. EMESIS: The only recommended method of including a poisoned patient to vomit is administration of “syrup of ipecacuanha or ipecac”. Syrup of Ipecac: Source: Root of a small shrub ( Cephaelis ipecacuanha or C. acuminata ) which grows well in West Bengal. Active principles: Cephaeline, emetine, and traces of psychotrine. Indications: Conscious and alert poisoned patient who has ingested a poison not more than 4 to 6 hours earlier.

6. CONTD… Mode of action: Local activation of peripheral sensory receptors in the gastrointestinal tract. Central stimulation of the chemoreceptor trigger zone with subsequent activation of the central vomiting centre.

7. CONTD… Dose: 30 ml (adult), or 15 ml (child), followed by 8 to 16 ounces, i.e. 250 to 500 ml approximately, of water. The patient should be sitting up. If vomiting does not occur within 30 minutes, repeat the same dose once more. If there is still no effect, perform stomach wash to remove not only the ingested poison but also the ipecac consumed. However the therapeutic doses of ipecac recommended above are not really harmful.

8. CONTRAINDICATIONS: RELATIVE: Very young (less than 1 year), or very old patient Pregnancy Heart disease Bleeding diathesis Ingestion of cardiotoxic poison Time lapse of more than 6 to 8 hours OBSOLUTE: Convulsions, or ingestion of a convulsant poison Impaired gag reflex Coma Foreign body ingestion Corrosive ingestion Ingestion of petroleum distillates, or those drugs which cause altered mental status (phenothiazines, antihistamines, opiates, ethanol, benzodiazepines, tricyclics). All poisons which are themselves emetic in nature

9. OTHER EMETICS: Apomorphine: Given subcutaneously, it causes vomiting within 3 to 5 minutes by acting directly on the chemoreceptor trigger zone. The recommended dose is 6 mg (adult), and 1 to 2 mg (child). Since apomorphine is a respiratory depressant it is contraindicated in all situations where there is likelihood of CNS depression. Obsolete emetics: Warm saline or mustard water Copper sulphate Zinc sulphate

10. 2. GASTRIC LAVAGE (STOMACH WASH): The American Academy of Clinical Toxicology (AACT), and the European Association of Poison Centres and Clinical Toxicology (EAPCCT) have prepared a draft of a position paper directed to the use of gastric lavage, which suggests that gastric lavage should not be employed routinely in the management of poisoned patients. There is no certain evidence that its use improves outcome, while the fact that it can cause significant morbidity (and sometimes mortality) is indisputable. Lavage should be considered only if a patient has ingested a life-threatening amount of a poison and presents to the hospital within 1 to 2 hours of ingestion.

11. INDICATIONS: Gastric lavage is recommended mainly for patients who have ingested a life-threatening dose, or Who exhibit significant morbidity and present within 1 to 2 hours of ingestion. Lavage beyond this period may be appropriate only in the presence of gastric concretions, delayed gastric emptying, or sustained release preparations. Some authorities still recommend lavage upto 6 to 12 hours post-ingestion in the case of salicylates, tricyclics, carbamazepine, and barbiturates.

12. PRECAUTIONS: Never undertake lavage in a patient who has ingested a non-toxic agent, or a non-toxic amount of a toxic agent. Never use lavage as a deterrent to subsequent ingestions. Such a notion is barbaric, besides being incorrect.

13. CONTRAINDICATIONS: Relative : Haemorrhagic diathesis, oesophageal varices, recent surgery, advanced pregnancy, ingestion of alkali, coma. Absolute : Marked hypothermia, prior significant vomiting, unprotected airway in coma, and ingestion of acid or convulsant or petroleum distillate, and sharp substances.

14. PROCEDURE: Explain the exact procedure to the patient and obtain his consent. If refused, it is better not to undertake lavage because it will amount to an assault, besides increasing the risk of complications due to active non-co-operation. Endotracheal intubation must be done prior to lavage in the comatose patient. Place the patient head down on his left lateral side (20 tilt on the table). Mark the length of tube to be inserted (50 cm for an adult, 25 cm for a child). The ideal tube for lavage is the “lavacuator” (clear plastic or gastric hose).

15. CONTD… In India however, the “Ewald tube” is most often used which is a soft rubber tube with a funnel at one end. Whatever tube is used, make sure that the inner diameter corresponds to at least 36 to 40 French size. A nasogastric tube used for gastric aspiration is inadequate and should never be used. In a child, the diameter should be at least 22 to 28 French, (Ryle’s tube may be sufficient). The preferred route of insertion is oral. Passing the tube nasally can damage the nasal mucosa considerably and lead to severe epistaxis. Lubricate the inserting end of the tube with vaseline or glycerine, and pass it to the desired extent. Use a mouth gag so that the patient will not bite on the tube.

16. CONTD… Once the tube has been inserted, its position should be checked either by air insufflation while listening over the stomach, or by aspiration with pH testing of the aspirate, (acidic if properly positioned). Lavage is carried out using small aliquots (quantities) of liquid. In an adult, 200 to 300 ml aliquots of warm (38 C) saline or plain water are used. In a child, 10 to 15 ml/kg body weight of warm saline is used each time. Water should preferably be avoided in young children because of the risk of inducing hyponatremia and water intoxication. It is advisable to hold back the first aliquot of washing for chemical analysis.

17. CONTD… In certain specific types of poisoning, special solutions may be used in place of water or saline. Lavage should be continued until no further particulate matter is seen, and the efferent lavage solution is clear. At the end of lavage, pour a slurry of activated charcoal in water (1 gm/kg), and an appropriate dose of an ionic cathartic into the stomach, and then remove the tube.

18. COMPLICATIONS: Aspiration pneumonia. Laryngospasm. Sinus bradycardia and ST elevation on the ECG. Perforation of stomach or oesophagus (rare).

19. 3. CATHARSIS: Catharsis is a very appropriate term when used in connection with poisoning, since it means purification. It is achieved by purging the gastrointestinal tract (particularly the bowel) of all poisonous material. The two main groups of cathartics used in toxicology include: Ionic or Saline Saccharides

20. I) IONIC OR SALINE: These cathartics alter physico-chemical forces within the intestinal lumen leading to osmotic retention of fluid which activates motility reflexes and enhances expulsion. However, excessive doses of magnesium based cathartics can lead to hypermagnesemia which is a serious complication. The doses of recommended cathartics are as follows: Magnesium citrate: 4 ml/kg Magnesium sulfate: 30 gm (250 mg/kg in a child) Sodium sulfate: 30 gm (250 mg/kg in a child).

21. II) SACCHARIDES: Sorbitol (D-glucitol) is the cathartic of choice in adults because of better efficacy than saline cathartics, but must not be used as far as possible in young children owing to risk of fluid and electrolyte imbalance (especially hypernatremia). It occurs naturally in many ripe fruits and is prepared industrially from glucose, retaining about 60% of its sweetness. Sorbitol is used as a sweetener in some medicinal syrups, and the danger of complications is enhanced in overdose with such medications when sorbitol is used as a cathartic during treatment. Dose of sorbitol: 50 ml of 70% solution (adult).

22. EFFICACY OF CATHARSIS: While cathartics do reduce the transit time of drugs in the gastrointestinal tract, there is no real evidence that it improves morbidity or mortality in cases of poisoning. Contraindications: Corrosives Existing electrolyte imbalance, paralytic ileus Severe diarrhoea, recent bowel surgery Abdominal trauma Renal failure.

23. 4. ACTIVATED (MEDICINAL) CHARCOAL: Activated charcoal is a fine, black, odorless, tasteless powder made from burning wood, coconut shell, bone, sucrose, or rice starch, followed by treatment with an activating agent (steam, carbon dioxide, etc.). The resulting particles are extremely small, but have an extremely large surface area. Each gram of activated charcoal works out to a surface area of 1000 square meters.

24. CONTD… Mode of action: Decreases the absorption of various poisons by adsorbing them on to its surface. Activated charcoal is effective to varying extent, depending on the nature of substance ingested. Dose: 1 gm/kg body weight (usually 50 to 100 gm in an adult, 10 to 30 gm in a child).

25. PROCEDURE: Activated charcoal is most effective when administered within one hour of ingestion. Administration in the prehospital setting has the potential to significantly decrease the time from toxin ingestion to activated charcoal administration, although it has not been shown to affect outcome. Add 4-8 times the quantity of water to the calculated dose of activated charcoal, and mix to produce a slurry or suspension. This is administered to the patient after emesis or lavage, or as sole intervention. The slurry should be shaken well before administration.

26. MULTIPLE DOSE ACTIVATED CHARCOAL: The use of repeated doses (amounting to 150 to 200 gm of activated charcoal) has been demonstrated to be very effective in the elimination of certain drugs such as theophylline, phenobarbitone, quinine, digitoxin, phenylbutazone, salicylates and carbamazepine. The actual dose of activated charcoal for multiple dosing has varied considerably in the available medical literature, ranging from 0.25 to 0.5 gm/kg every 1 to 6 hours, to 20 to 60 gm for adults every 1, 2, 4, or 6 hours. The total dose administered is more important than frequency of administration.

27. CONTD… DISADVANTAGES: Unpleasant taste Provocation of vomiting Constipation/diarrhoea Pulmonary aspiration Intestinal obstruction (especially with multiple-dose activated charcoal). CONTRAINDICATIONS: Absent bowel sounds or proven ileus Small bowel obstruction Caustic ingestion Ingestion of petroleum distillates.

28. 5. WHOLE BOWEL IRRIGATION (WHOLE GUT LAVAGE): This is a method that is being increasingly recommended for late presenting overdoses when several hours have elapsed since ingestion. It involves the instillation of large volumes of a suitable solution into the stomach in a nasogastric tube over a period of 2 to 6 hours producing voluminous diarrhoea. Previously, saline was recommended for the procedure but it resulted in electrolyte and fluid imbalance. Today, special solutions are used such as PEG-ELS ( i.e. polyethylene glycol and electrolytes lavage solution combined together, which is an isosmolar electrolyte solution), and PEG-3350 (high molecular weight polyethylene glycol) which are safe and efficacious, without producing any significant changes in serum electrolytes, serum osmolality, body weight, or hematocrit.

29. CONTD… Today, special solutions are used such as: PEG-ELS ( i.e. polyethylene glycol and electrolytes lavage solution combined together, which is an isosmolar electrolyte solution), and PEG-3350 (high molecular weight polyethylene glycol) which are safe and efficacious, without producing any significant changes in serum electrolytes, serum osmolality, body weight, or hematocrit.

30. INDICATIONS: Ingestion of large amounts of toxic drugs in patients presenting late (>4 hours post-exposure) Overdose with sustained-release preparations. Ingestion of substances not adsorbed by activated charcoal, particularly heavy metals. Ingestion of foreign bodies such as miniature disc batteries (button cells), cocaine filled packets (body packer syndrome), etc. Ingestion of slowly dissolving substances: iron tablets, paint chips, bezoars, concretions, etc.

31. PROCEDURE: Insert a nasogastric tube into the stomach and instill one of the recommended solutions at room temperature, at a rate of 2 liters per hour in adults, and 0.5 liter per hour in children. The patient should preferably be seated in a commode. The use of metoclopramide IV, (10 mg in adults, 0.1 to 0.3 mg/kg in children) can minimize the incidence of vomiting. The procedure should be continued until the rectal effluent is clear, which usually occurs in about 2 to 6 hours.

32. COMPLICATIONS: Vomiting Abdominal distension and cramps Anal irritation. Contraindications: Gastrointestinal pathology such as obstruction, ileus, haemorrhage, or perforation.

33. REFERENCE/BIBLIOGRAPHY: V. V. Pillay - Modern medical toxicology - 4 th edition